Wine cooler not cooling at all; interior is at room temperature but lights and display work, no error code shown.

Safety first: Unplug the appliance before removing rear panels or touching compressor wiring.

Steps to diagnose:

• Check settings: Confirm the unit is switched on, not in demo mode, and the set temperature is below ambient.
• Listen for operation: With the unit plugged in, listen for compressor and fan noise. If completely silent, suspect control or compressor circuit.
• Inspect rear compartment: Remove the rear lower panel and check for loose or burnt wires at the compressor and main PCB.
• Replace start device: If the compressor is warm but not running and the start relay/PTC looks damaged, replace it with a Siemens-compatible part.

If the compressor still does not run, the main control PCB or the compressor itself may be faulty. These require professional diagnosis and often sealed-system work.